/*	$OpenBSD: rf_pqdeg.c,v 1.4 2000/01/11 18:02:22 peter Exp $	*/
/*	$NetBSD: rf_pqdeg.c,v 1.5 2000/01/07 03:41:04 oster Exp $	*/

/*
 * Copyright (c) 1995 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Author: Daniel Stodolsky
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

#include "rf_archs.h"

#if	(RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0)

#include "rf_types.h"
#include "rf_raid.h"
#include "rf_dag.h"
#include "rf_dagutils.h"
#include "rf_dagfuncs.h"
#include "rf_dagffrd.h"
#include "rf_dagffwr.h"
#include "rf_dagdegrd.h"
#include "rf_dagdegwr.h"
#include "rf_etimer.h"
#include "rf_pqdeg.h"
#include "rf_general.h"
#include "rf_pqdegdags.h"
#include "rf_pq.h"

/*
 * Degraded mode dag functions for P+Q calculations.
 *
 * The following nomenclature is used.
 *
 *   PQ_<D><P><Q>_Create{Large,Small}<Write|Read>DAG
 *
 * where <D><P><Q> are single digits representing the number of failed
 * data units <D> (0,1,2), parity units <P> (0,1), and Q units <Q>, effecting
 * the I/O. The reads have only  PQ_<D><P><Q>_CreateReadDAG variants, while
 * the single fault writes have both large and small write versions.
 * Single fault PQ is equivalent to normal mode raid 5 in many aspects.
 *
 * Some versions degenerate into the same case, and are grouped together below.
 */


/* Reads, single failure. */

/* We have parity, so we can do a raid 5 reconstruct read. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateReadDAG)
{
	rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
	    &rf_pRecoveryFuncs);
}


/* Reads double failure. */

/*
 * Q is lost, but not parity.
 * So we can a raid 5 reconstruct read.
 */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_101_CreateReadDAG)
{
	rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
	    &rf_pRecoveryFuncs);
}

/*
 * Parity is lost, so we need to
 * do a reconstruct read and recompute
 * the data with Q.
 */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_110_CreateReadDAG)
{
	RF_PhysDiskAddr_t *temp;
	/* Swap P and Q pointers to fake out the DegradedReadDAG code. */
	temp = asmap->parityInfo;
	asmap->parityInfo = asmap->qInfo;
	asmap->qInfo = temp;
	rf_CreateDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags, allocList,
	    &rf_qRecoveryFuncs);
}

/*
 * Two data units are dead in this stripe, so we will need read
 * both P and Q to reconstruct the data. Note that only
 * one data unit we are reading may actually be missing.
 */
RF_CREATE_DAG_FUNC_DECL(rf_CreateDoubleDegradedReadDAG);
RF_CREATE_DAG_FUNC_DECL(rf_CreateDoubleDegradedReadDAG)
{
	rf_PQ_DoubleDegRead(raidPtr, asmap, dag_h, bp, flags, allocList);
}

RF_CREATE_DAG_FUNC_DECL(rf_PQ_200_CreateReadDAG);
RF_CREATE_DAG_FUNC_DECL(rf_PQ_200_CreateReadDAG)
{
	rf_CreateDoubleDegradedReadDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList);
}


/* Writes, single failure. */

RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateWriteDAG);
RF_CREATE_DAG_FUNC_DECL(rf_PQ_100_CreateWriteDAG)
{
	if (asmap->numStripeUnitsAccessed != 1 &&
	    asmap->failedPDAs[0]->numSector !=
	    raidPtr->Layout.sectorsPerStripeUnit)
		RF_PANIC();
	rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp,
	    flags, allocList, 2, (int (*) (RF_DagNode_t *))
	    rf_Degraded_100_PQFunc, RF_FALSE);
}

/* Dead  P - act like a RAID 5 small write with parity = Q. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_010_CreateSmallWriteDAG)
{
	RF_PhysDiskAddr_t *temp;
	/* Swap P and Q pointers to fake out the DegradedReadDAG code. */
	temp = asmap->parityInfo;
	asmap->parityInfo = asmap->qInfo;
	asmap->qInfo = temp;
	rf_CommonCreateSmallWriteDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList, &rf_qFuncs, NULL);
}

/* Dead Q - act like a RAID 5 small write. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_001_CreateSmallWriteDAG)
{
	rf_CommonCreateSmallWriteDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList, &rf_pFuncs, NULL);
}

/* Dead P - act like a RAID 5 large write but for Q. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_010_CreateLargeWriteDAG)
{
	RF_PhysDiskAddr_t *temp;
	/* Swap P and Q pointers to fake out the code. */
	temp = asmap->parityInfo;
	asmap->parityInfo = asmap->qInfo;
	asmap->qInfo = temp;
	rf_CommonCreateLargeWriteDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList, 1, rf_RegularQFunc, RF_FALSE);
}

/* Dead Q - act like a RAID 5 large write. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_001_CreateLargeWriteDAG)
{
	rf_CommonCreateLargeWriteDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList, 1, rf_RegularPFunc, RF_FALSE);
}


/* Writes, double failure. */

/* Lost P & Q - do a nonredundant write. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_011_CreateWriteDAG)
{
	rf_CreateNonRedundantWriteDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList, RF_IO_TYPE_WRITE);
}


/*
 * In the two cases below, a nasty case arises when it's a write for a
 * (strict) portion of a failed stripe unit and parts of another su.
 * For now, we do not support this.
 */

/* Lost Data and  P - do a Q write. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_110_CreateWriteDAG)
{
	RF_PhysDiskAddr_t *temp;

	if (asmap->numStripeUnitsAccessed != 1 &&
	    asmap->failedPDAs[0]->numSector !=
	    raidPtr->Layout.sectorsPerStripeUnit) {
		RF_PANIC();
	}
	/* Swap P and Q to fake out parity code. */
	temp = asmap->parityInfo;
	asmap->parityInfo = asmap->qInfo;
	asmap->qInfo = temp;
	rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList, 1, (int (*) (RF_DagNode_t *))
	    rf_PQ_DegradedWriteQFunc, RF_FALSE);
	/* Is the regular Q func the right one to call ? */
}

/* Lost Data and Q - do degraded mode P write. */
RF_CREATE_DAG_FUNC_DECL(rf_PQ_101_CreateWriteDAG)
{
	if (asmap->numStripeUnitsAccessed != 1 &&
	    asmap->failedPDAs[0]->numSector !=
	    raidPtr->Layout.sectorsPerStripeUnit)
		RF_PANIC();
	rf_CommonCreateSimpleDegradedWriteDAG(raidPtr, asmap, dag_h, bp, flags,
	    allocList, 1, rf_RecoveryXorFunc, RF_FALSE);
}

#endif	/* (RF_INCLUDE_DECL_PQ > 0) || (RF_INCLUDE_RAID6 > 0) */
